A known procedure for treating vertebral compression fractures and other bone-related disorders is vertebral augmentation with bone cement. Vertebral augmentation can be performed by the direct injection of liquid cement into the collapsed vertebral body (commonly known as “vertebroplasty”). Vertebral augmentation can also be performed after the restoration of the vertebrae to near normal vertebral body anatomy and creation of an internal cavity with the use of an inflatable bone tamp. This minimally invasive procedure is commonly known as “kyphoplasty” (see, for example, U.S. Pat. Nos. 4,969,888 and 5,108,404). During the kyphoplasty procedure, the inflatable bone tamp is inserted through a small skin incision which accommodates a working tube passed into the vertebral body. Inflation of the bone tamp compresses the cancellous bone and desirably moves the fractured cortical bone to its pre-fractured orientation, creating a cavity within the vertebral body that can then be filled with a settable material such as a cement or any number of synthetic bone substitutes. In effect, the procedure sets the vertebral body at or near its pre-fracture position and creates an internal cast, protecting the vertebral body from further fracture and/or collapse.
As compared to a traditional vertebroplasty procedure, kyphoplasty restores the vertebrae to a pre-fractured condition and the injected bone filler is less likely to leak out of the vertebral body during a kyphoplasty procedure. However, under some circumstances, it has been observed that unpredictable reductions can occur with the kyphoplasty technique in chronic or partially healed collapsed vertebral bodies. Under those circumstances, the surgeon would typically resort to a large, open operation to re-align any post-traumatic kyphosis. Further, inadequate reductions can occur with certain other spinal deformities such as scoliosis and kyphosis using the known techniques and surgical tools. The large, open operations can carry with them significant morbidity in an already physiologically compromised elderly population. The principle benefit of a percutaneous minimally invasive approach, which is the hallmark of the kyphoplasty procedure, is the minimal morbidity associated with the procedure. In this light, additional tools are required to further the kyphoplasty technique, achieve better anatomic re-alignment of the spine, and maintain the minimally invasive nature of the surgery. The additional tools will be deployed through small working portals and be able to achieve the desired strategic vertebral osteotomies to move bone in three dimensional space. One such desirable tool would provide a minimally invasive means to safely cut the lateral (or side) wall of a vertebral body, such as a lateral wall with a prior, and at least partially healed, compression fracture.